


Denial

by Nanenna



Series: Devil's Threesome [3]
Category: Undertale (Video Game)
Genre: AfterDoubleDeath (Undertale Ship), Aftercare, Aftertale Sans (Undertale) - Freeform, Aftertale Sans/Reapertale Sans/Reapertale Sans (Undertale), Alternate Universe - Aftertale (Undertale), Alternate Universe - Demons, Alternate Universe - Monsters Weren't Sealed Underground, Alternate Universe - Reapertale (Undertale), Alternate Universe - Twins, Amoral Characters, Amorality, Blood and Injury, Body Dysmorphic Disorder, Dark, Demons, Double Penetration in One Hole, Ecto-Genitalia (Undertale), Implied Violence, Injury, M/M, Major Character Injury, Multi, Oral Sex, Overstimulation, Patchwork AU, Reapertale Sans (Undertale), Sibling Incest, Threesome - M/M/M, Unrealistic Sex, Vaginal Fingering
Language: English
Status: Completed
Published: 2020-05-09
Updated: 2020-05-09
Packaged: 2021-03-03 01:53:28
Rating: Explicit
Warnings: Rape/Non-Con
Chapters: 1
Words: 4,336
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24096883
Author URL: https://archiveofourown.org/users/Nanenna/pseuds/Nanenna
Summary: Two warriors, an alchemist, a bard, and a mage should have been plenty for this dungeon. They were wrong. Now Geno’s lost, alone, mortally injured, and worst of all: facing down two demons with creepy, empty sockets and strangely alluring smiles.
Relationships: Sans/Sans (Undertale)
Series: Devil's Threesome [3]
Series URL: https://archiveofourown.org/series/1540084
Comments: 23
Kudos: 112





	Denial

**Author's Note:**

  * Inspired by [Reapertale](https://archiveofourown.org/external_works/763596) by Renrink. 
  * Inspired by [Aftertale](https://archiveofourown.org/external_works/763599) by Crayon Queen. 



> Just in case you somehow missed it: this fic contains **rape/non-con**. While a form of consent is given, due to the intentional lack of communication and manipulative actions taken this can't be called anything else. Continue reading at your own risk.
> 
> Okay so not actually a sin this time, but I could still see a demon of some kind using something like denial as a weapon. That insidious little voice in the back of your head whispering: “It’s not a big deal. I can totally take this asshole in a fight. I’ve got this under control. I can quit any time I want. Everyone fights sometimes, no relationship is perfect.”

Geno stumbles and staggers, the only thing that keeps him from hitting the floor is the hand already on the wall next to him. ~~At this point he~~ ~~i~~ ~~sn’t sure if he would be able to get up again~~. He wheezes and leans heavily against the wall as he gathers himself slowly back together, then glances behind him to see what had tripped him.

A branch.

A goddamned branch sitting against the wall of a dungeon at least six flights of stairs straight down into the ground, not a window or even a potted plant anywhere in sight. How in hell had that thing even gotten down there?!

Geno grumbles and turns away from the branch. His left hand, the one not holding himself up with a wet, cold, dirty stone wall, came up to rub at his eye socket. His left one, the one that still actually works. The hand left a smear of something, Geno isn’t sure what (monsters don’t bleed, and mana exposed to air evaporates quickly), across his face. Geno grimaces, then goes back to trying to hold his shoulder together. The wound running from his right shoulder, across his ribs, and down to his left iliac crest has been leaking for ~~days?~~ ~~weeks?~~ ~~months?~~ hours and hasn’t stopped yet, but that doesn’t stop it from hurting with every jarring step. Not like his right eye, oh it’s still blind, but the pain has long since faded. Instead the bone around the socket has gone numb and feels funny. Probably because it’s numb. Not that it matters, Geno doesn’t think he’s getting out of here alive.

He takes a few more deep breaths, then braces himself to start ~~limping~~ walking along the hallway. There’s no going back anyway, not when he and the rest of his party arrived and the doors promptly slammed shut and sealed them in, and certainly not now when he doesn’t think he could even lift his feet high enough to go up a set of stairs.

The hallway ends on an arched entryway with no door in sight, not that it’s going to make a difference. Geno stumbles through and lets himself half collapse against the wall, the clacks of many heavy locks on the door that wasn’t there just a second ago clicking into place echo through the large room. Geno grits his teeth, keeping his bad eye towards the wall and tenses up, ready to push off the wall to dodge whatever’s thrown his way. So far it’s been about a 50-50 chance something will attack him in the hallways, but there’s always been something in the rooms.

“well look what we have here.”

Geno’s head whips around, finding nothing behind him but an expanse of wall broken only by the door he’d just come through.

“a little lost soul, ripe for the reaping.”

Geno spun back to face forward, but there was nothing ahead of him but a long wall leading to the far end of the room, where swaths of black fabric are draped over the far wall. His lone working pip darts about the rest of the room, noting a massive stone chair that seems to have decorations chiseled into it on a small raised stone dais against the far wall, glittering stones attached to thin metal chains are draped over the chair’s back and seat and dripping over the arms. Two rows of metal chairs that seemed to grow out of the stone floor like twisted, dead trees form an aisle leading to the stone chair. There didn’t seem to be any way out, but he wouldn’t be sure until he checks behind the convenient looking fabric.

“and what a sweet little soul it is.”

Geno resists the urge to shake his head, how had he gotten so lost in reverie he’d forgotten the malevolent being in here with him? “show yourself!” he demands angrily. He’s fought his way this far, he’s not going to go down without at least one more fight. Magic bristles along his bones and gathers in his working socket.

“so demanding, do you even know who you’re ordering around?”

“how can i when you hide like a coward?” Geno shoots back in the most bored tone. His pip drifts over to the far wall, perhaps he can just sidle along to it and look for the exit?

“he’s got a point there.”

Geno’s head whips back to the center of the room. There’s a moment of silence, then something dark enters his vision. From above. Geno flinches, it’s all he can do not to fall over as he looks up to find a demon dressed in flowing black robes held closed with ropes floating down until the ragged edges of his robes pool on the immaculately clean floor. Geno manages to slap a wet, sticky hand over his teeth before he shrieks in pure ~~terror~~ surprise.

The demon holds out a hand and grins at him, “the name’s grim, nice to meetcha.”

Geno glares at the demon, he’s floating a few steps away from Geno, he’ll have to leave the wall behind to shake his hand. It’s very clearly a trap, Geno would probably be better off just attacking him and hoping for the best.

“c’mon, pal, don’t you know how to greet a new friend?” The demon holds his hand a little higher, sockets half lidded like Geno isn’t a threat at all.

Geno shifts, getting ready to pull out all the stops and just attack this Grim fellow with everything he has, but his fingers brush against the ~~dusty~~ scarf around his neck. Suddenly he’s just tired, a (heh) bone deep exhaustion that leaves him wondering why he’s even bothering. What’s the worst that can happen? Grim springs whatever trap this is and Geno dies? He’s going to die down here sooner or later, maybe if he’s lucky it’ll be a quick death. ~~Not like Undyne, slowly slipping away as Alphys cries and begs and screams and can’t do a single thing to stop it.~~

Geno pushes off the wall and takes the two small, trembling steps between him and Grim. “call me geno,” he says as he takes the offered hand.

Grim stares at where their hands are joined for a moment, his grin spreading wider, then slowly looks back up at Geno’s face. There’s a strange glint to his empty sockets as he says, “and that’s reaper.”

A pair of arms snake over Geno’s shoulders to drape possessively over his ribs.

Geno does shriek this time, volatile magic and whizzing bullets crackling to life around him as he kicks and flails.

Neither demon lets him go, even though Geno can _feel_ his attacks connecting. In fact Grim pulls Geno in closer to wrap his arm around both Geno and Reaper, trapping him in the middle of some sort of awful three way hug.

“leggo! lemme go you fucking demons!”

“he’s a feisty one,” one of them says in Geno’s aural canal.

“i like that, let’s keep him.”

“of course!”

“what? no!” Geno starts struggling harder, but it does him no good. His feet are lifted from the ground and they start drifting down the aisle towards the fancy chair. Between them and the chair the air shimmers and darkens, a swirling black vortex opens. Geno doesn’t want to go anywhere near that thing! Out of desperation he cranes his head into a painful angle and manages to bite one of Reaper’s arms.

“ow! he bit me!”

“oh, so he’s a biter? wonder if he scratches too.”

“won’t it be fun to find out?”

Geno growls and gives up on biting. Well, half his skull isn’t really working anyway, may as well put it to some use. He tries to headbutt Grim, but in the same moment they spin, or maybe just the world does, and twist. There’s a moment of darkness that lasts all too long. Geno blinks to try and clear his vision, when it adjusts he finds himself staring up at swaths of dimly lit dark fabric overhead, his back against something soft and padded. The room smells different too, like a closed in, stuffy space rather than a dank, musty dungeon. Then he notices his arms are being held over his head against the soft thing he’s on, one demon looking down at him with those eerie, blank sockets, the other seems to be holding down his legs.

The demon looming over Geno places his hand on Geno’s sternum, right over where his Soul is fluttering painfully. ~~He thinks it’s fluttering painfully anyway. It should be painful, right?~~ “there we go, were you searching for us long?”

“i wasn’t searching for you at all!” Geno spits in ~~confusion~~ anger.

“maybe not us specifically, but you were searching,” the other demon says.

“aren’t we lucky we were the first to find you.”

“i was searching for a way out!”

The demon looming over Geno looks down at the other one, then they both burst into laughter. Geno’s Soul flutters _painfully_ again.

“and you weren’t even the first to find me,” Geno adds on defensively. “i killed a lot of demons before meeting you assholes.”

“sure, imps and little lesser demons.”

“riffraff.”

“weaklings.”

“unworthy.”

Geno’s Soul did something funny then, it felt like a bell that had been struck, the resulting sound lingering and echoing through the hollows of his bones.

The demons take that moment of confusion to quickly strip Geno of his clothes, starting with his brother’s scarf. Geno whimpers, “wait, not that.”

“you wanna fuck with someone’s memento mori wrapped around your neck?”

“oooooh! kinky.”

“no, that’s not…”

The demon sitting in front of Geno lets his hands drop down from the scarf, trailing over ribs, his spine, down to his iliac crests, then back up. Whichever of the brothers is in front of him (and right now Geno really wishes he could tell them apart) is being so gentle, his touches just firm enough to not tickle. It’s such a contrast to all the pain and stress he’s been stewing in for the last… Geno isn’t even sure how long. It feels like his whole world has been nothing but pain of every kind for the last forever. To actually have someone touch him gently, the Intent of _pleasure_ , muffled by the layers of clothing still between his bones and the demon’s hand but still there. Geno moans and arches into the touch.

“there we go, doesn’t that feel good?”

“like you even have to ask.” They both snicker.

“scarf on or off?”

Geno can feel fingers ruffling over the fabric. It takes a moment for his mind to catch up to the question, “o-off,” he stutters, then moans again when the other demon (and fuck it, he’s just going to call that one Grim and if he’s wrong that’s their problem) gets his hands under Geno’s coat.

The scarf slips from his neck and is placed to the side. Geno’s blind side, unfortunately, so he’s not sure exactly what happened to it. Then both demons return to undressing him, the _pleasure_ increasing with each layer of clothing they peel off. Reaper’s fingers skim along the cut through Geno’s ribs. “i can’t believe you haven’t healed this yet, doesn’t it hurt? or maybe you like a little pain?”

Geno was about to retort that he wasn’t going to go around eating random things he **found lying on the ground in a fucking dungeon** ~~again. He’d seen what the fruit had done to Undyne, but~~ ~~by then~~ ~~he was alone and desperate and sure he wasn’t ever getting out, at least he would take some of these goddamned demons out with him~~ , but then Reaper presses down on the wound just a little and the mix of pleasure and pain alongside the gentle touches full of _desire_ and _pleasure_ completely undoes Geno. He arches again, leaning heavily into the bony body behind him and makes an embarrassingly sexual sound. His ecto summons itself into place so fast it actually makes a snapping sound.

There’s a pause as the two demons take in the plump ecto-body that Geno suddenly has spanning from his ribs down to his knees, “oh he **really** liked that.”

“no… i…” Geno stutters, more confused than anything else. That had never happened before! But he couldn’t really deny he had liked that, he could already feel slick soaking into his pants.

Grim shifts down, pulling Geno’s underwear off with the movement, then spreads Geno’s legs wide. The only warning Geno has of what is about to happen is a puff of cold breath against his dripping entrance, then there’s a tongue running up his lips. The direct magic on magic amplifies the Intent, a shot of _pleasure_ intermixed with _desire_ and _eagerness_ that shoots straight from his pussy to his Soul. His thighs squeeze the skull between them, as if afraid Grim would pull away.

The wound in his chest burns as the last layer of clothing is peeled away, then he’s let back down to lay on the bed. Geno feels unmoored, his hands fist into the thick blanket under him. There’s a shift of fabric next to him, but Geno’s distracted by the tongue that had been teasing him moments before suddenly delving into him. Geno gasps, then looks down. All he can see is an expanse of glowing red ecto-flesh and the top of Grim’s skull, his empty eye sockets looking right at Geno.

Wait, red ecto? That’s wrong, Geno’s magic is an icy, searing blue. It shouldn’t be red, that’s not right. That’s not… that’s not his body…

“yeah, let’s do that.”

Before Geno can process the comment Grim withdraws, then he’s suddenly flipped onto his front. He’s unprepared for it and ends up chest down on the bed. He hisses in pain to feel his wound ground into the bedding like that, then hisses in pleasure when Grim dives back in face first.

“here, how about you let me feel that mouth of yours.”

Geno looks up to find himself eye to eye with a dick such a dark shade of blue it’s almost black. He looks up further to find Reaper sitting before him, his robes nowhere in sight. Geno’s tongue summons itself on pure instinct and he can suddenly taste the liquid that’s been slowly dripping from the crack inside his skull and into his mouth only to drip back out from between his teeth. It tastes like a mix of spicy and sweet that’s too much like that weird, red, upside-down-Soul-shaped fruit he’d eaten out of desperation. The one that had felt like it was burning him from the inside out but had left him sparking with more magic than he knew what to do with.

A thumb forces itself into the corner of Geno’s mouth, he opens it to let Reaper pull him onto his dick at the same moment Grim pulls out and replaces his tongue with a finger, followed quickly by another. All of Geno’s thoughts mercifully shatter and drift away. He lets himself just focus on the here and now, focus on relaxing his jaw for Reaper as he grips his skull and pumps his hips, focus on the way Grim’s fingers flex and curl and scissor inside him.

“such a sweet little mouth you have,” Reaper croons.

Geno grunts and glowers, he’s not **that** little! But there’s not much else he can do to protest with his mouth full of dick.

“you gotta feel this next,” Reaper says to Grim. “he’s so warm.”

“he’s a spicy one,” Grim agrees, adding a third finger.

Geno moans again, louder this time, causing Reaper to stutter and groan himself. A finger starts circling Geno’s clit, little teasing promises that has Geno trembling in anticipation. Reaper has picked his pace back up, one hand holding Geno’s skull and the other still with a thumb in the corner of Geno’s mouth. He uses his leverage to thrust deeper, the head of his dick hitting the back of Geno’s mouth. As seems to be the theme of the… evening? morning? afternoon? Geno’s throat joins the party of its own accord.

“yeah, that’s a good little boy, make a nice little throat for me to fuck. you like that? you like gagging on my dick?” Reaper thrusts deep again.

Geno gags, tears well up in his good eye. Grim chooses that moment to pinch his clit, leaving Geno choking and moaning.

“i think he’s just about ready,” Grim says in a far too satisfied voice.

“alright, do you want to start now or…?”

“tempting as that is, we’d better do this right. i do want to feel that foul mouth of his for myself, next time.”

Geno would argue back that they’re the ones spouting bad dirty talk, but fingers and dick pulling out of him leave Geno feeling suddenly bereft. He whimpers at just how painfully empty he feels. Grim pulls him upright, Reaper helping by lifting him up under his armpits, until he’s sitting in his lap with his back to his chest. There’s a bit of shuffling as Reaper slides right up to them, his ribs grazing Geno’s. Their legs slip easily into place, leaving Geno kneeling over their laps with quickly cooling slick dripping down his thighs. Reaper pulls Geno’s arms over his shoulders and around his neck, then one hand slips down to a hip while the other disappears down between them. Geno can feel the arm moving, but he’s not sure what exactly Reaper’s doing. Grim slips a hand down to Geno’s other hip and the other down his front until he finds Geno’s lips and spreads them. Then there’s a pair of cocks nudging at his entrance and Geno gasps.

Grim leans forward and presses his teeth to the side of Geno’s skull, there’s the spark and tingle of a kiss before he whispers, “relax, we’ll go slow. we want to do this right.”

The heads pop in, followed by a trio of moans. The cocks are chilly, but their touch sends sparks of tingling magic and _pleasure desire_ singing through his Soul, doing far more to warm him than any physical heat could.

“relax,” Reaper murmurs against the other side of Geno’s skull, a tingling kiss added for emphasis. “we got you, just relax and let us take care of you.”

The rest of their hands end up on Geno’s hips, slowly pushing him down onto their cocks. Geno let’s them, slowly spreading him wider as he sinks further and further down. The delightful burn of the stretch mingles so nicely with the little sparks of _pleasure_ from the contact.

Once Geno’s fully sitting on them, feeling full, full, full to overflowing, they pause. All three are breathing heavily, Reaper’s and Grim’s hands roam over his body, both murmuring little praises that shouldn’t have Geno’s Soul fluttering the way it does. And then it’s not enough and Geno’s arms tighten around Reaper’s neck because he just wants to **move**. Both pairs of hands are back on his hips, holding him still as one of them rocks their hips up, then the other. Geno gasps and chokes on an aborted scream.

“mmm… yeah, that feel good? god you’re so tight. so sweet and perfect. like you’re made for us. go ahead and sing. i bet you sing so prettily.”

Geno wasn’t sure anymore which demon was saying what, their identical voices blending together as they swirled around in his skull. They keep moving, at first just little testing thrusts as the pair feel each other and find their rhythm, that alone is almost too much for Geno. Then they start thrusting in earnest, in counterpoint no less. He’s never left empty, just full, full, and overfull, the ridges on their dicks catching and plucking at his insides but never quite tips over into pain as the cocks radiate nothing but _pleasure pleasure pleasure_. No, the pain is saved for the biting sparks from his ribs catching against Reaper’s with every thrust. Geno can’t help the sounds coming out of him, the moans and gasps that Reaper swallows down in a kiss that just goes on and on and on. Thank god skeletons don’t need to breathe.

“he’s so tight,” Grim moans, then leans down to nip and nibble at Geno’s neck and shoulder before **biting down**.

Geno cums, or thinks he does. His pussy flutters and the expected wave of pure _bliss_ crashes through him, but the wave echoes off his Soul differently than it ever has before. It feels smaller somehow. Which is weird, right? And impossible. Not that he has the time or desire to think about any of that at the moment, he’s too busy choking on the tongue currently deep down his throat. Geno knows ecto-biology is pretty damn flexible but just how long Reaper’s tongue is is kind of mind blowing.

Geno arches back, pressing into Grim as his hands scrabble at Reaper’s scapulae. Reaper finally pulls back from the kiss, peppering his cheeks and jaw with little tingling kisses.

“god, he feels good.”

“so close, oh fuck, oh fuck!”

They both suddenly grind to a halt, both sets of hands pressing him down, down, down until they’re so deep Geno swears he can taste them. They both cry out and a shot of cold magic overflowing with _pleasure desire bliss ours OURS_ _ **OURS**_ floods his insides. Geno tenses and screams, pulling Reaper close as he presses back into Grim again.

Geno goes limp, flopping forward into Reaper’s arms. They stay like that for a long moment, the three of them gasping and panting in each other’s arms. That’s when Geno notices how hard he’s been sweating the whole time, suddenly the chill of the room, of his partners’ magic, of his sweat dripping down his bones hits Geno and he shivers.

“so good for us, so damn good for us,” one of them murmurs.

“like you were made just for us,” the other agrees.

Their hands are petting over Geno, their teeth sparking with the clack of little skeleton kisses over his skull, his face, his neck, his shoulders. Geno twitches as they pull out, the twinges from his abused pussy bordering just shy of painful. They lay him against pillows he didn’t even know were there and shivers again. The shivers don’t really stop this time, it’s weird, physical cold shouldn’t affect him like this but he’s just so damn cold. The two demons cuddle up to him, one on each side, and their magic may be physically cold (just a little chilly, really, it reminds him of the chill of stone in the shade or damp earth) but it’s still magic and there’s a vibrancy to all magic that helps ease his shivering.

One of the demons, Geno’s lost track of which one’s which again but right now he can’t be assed to care, grunts.

“yeah,” the other responds.

There’s frantic movement above him, Geno cracks his good eye open (when had he closed it?) to see the results of a rock-paper-scissors game above him. One has rock, the other paper. Paper covers Rock’s fist with a wide grin before laying back down and snuggling up to Geno like some kind of bony bear.

Rock groans in dismay, but pushes Geno more towards Paper before leaving the bed. One of their dark robes gets thrown over Geno, Paper tugging it this way and that a little until he’s satisfied before going back to snuggling. He peppers Geno’s skull with little skeleton kisses that tingle with _affection satisfaction soothing_ Intent.

“you’re perfect,” clack, “so perfect,” clack, “our perfect little mate,” clack, clack, clack, “god we’re so lucky we found you.”

Rock settled back onto the bed and added a few kisses of his own before pulling up the robe. Geno whines, it’s surprisingly warm and comfortable for such rough looking fabric. But then something warm and soft and wet is gently wiping over him. Geno cracked his good socket open again (why does it keep closing?) to see one of the demons with a bowl next to him gently washing Geno. Geno closes his eye and lets the demon do his work. When he was done an actual blanket was pulled over them, a chilly but vibrantly warm body on either side of him.

“go to sleep, precious.” A smooch on the side of his skull.

“you’ve more than earned it.” A smooch on the other side of his skull.

Geno is so tired and ~~deliciously~~ achy that he doesn’t have much choice in obeying the command. Before he knows it he’s drifted off and dead to the world.

* * *

Grim and Reaper had propped themselves up on one elbow each, looking down on their new acquisition as their free hands traced over the jagged curves of his broken bones. They smile at each other and hold a silent conversation that won’t wake their exhausted lover.

“poor little thing doesn’t know what he wants.”

“he’s in transition, what he wants is changing.”

“i can’t believe he made it all the way down to our level all by himself.”

“i can’t believe how much of his mortal soul he had left, it’s going to take a while to burn through the rest.”

“mmm… though we managed to burn through quite a bit just now.”

“even with us to guide and speed him along he’s still going to take quite a while to fully awaken.”

“he’s going to be strong when he does, really strong.”

“and ours, all ours.”

“yup, ours and no one else’s. pops and bro can meet him after he’s awakened.”

The demon hums in thought, “they can meet him a week after he’s awakened, if we let him off his back by then.”

They both chuckle at that. The pair settles down to doze next to Geno, continuing to trace swoops and swirls and demonic runes over their little acquisition’s bones and ecto-flesh.

**Author's Note:**

> Incorrect use of memento mori, but it just feels like the right term for this so whatever. (I suppose “reliquary” could have worked, but I like “memento mori” better.)  
>   
> So while this is clearly not directly related to it, this particular pairing is inspired by Golden_AU’s _Of Tragedy and Death_ and _1E99(Forever)_. Golden, I know this isn’t the situation we were talking about but here it is! “Gee Geno, why does your author let you have two Reapers?” Geno, of course, would tell you quite loudly that he doesn’t want either one. Just let them spoil you, Geno!


End file.
